• Title/Summary/Keyword: synthesize

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One-Dimensional Heterostructures Based Nanodevices

  • Myung, Nosang V.
    • Proceedings of the Materials Research Society of Korea Conference
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    • 2009.11a
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    • pp.3.1-3.1
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    • 2009
  • Nanotechnology has beenrapidly evolved from passive nanostructures where nanostructures with steadystructures and functions often used as parts of a product to activenanostructures which change their properties during use. Startingaround 2010, it is anticipated that researchers will cultivate expertise withsystems of nanostructures, directing large numbers of intricate components tospecified needs. One dimensional (1-D) nanostructures suchas nanowires and nanotubes are extremely attractive building blocks for nextgeneration devices because of their high surface to volume ratio and uniquesize dependent properties. In addition, their extremely high aspectratio offers researchers the potentials to build axial or radialheterostructures to integrate multiple functionality from intrinsic propertiesof the material or through interfacial phenomena. Spatialmanipulation and the ability to assemble and position nanostuructures in acontrolled matter so they are registered to define spaces is also a criticalstep toward scalable integration in high density nanodevices. In thispresentation, a generalized template directed electrodeposition with ancillaryassembly, contact will be presented to synthesize axial and radialheterostructures in cost-effective matter and these individual nanostructureswill be applied to spintronics, gas and biological sensors and thermoelectrics.

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Electrochemistry Coating Method (전기화학 Coating Method)

  • Lee, Sang-Heon
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2009.06a
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    • pp.372-373
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    • 2009
  • In this work, the effects of substrate on the formation of YBaCuO by CVD were investigated by observing the microstructure and the crystallographic orientation and by measuring the temperature dependence of electrical resistance. Source materials used to synthesize the YBaCuO superconducting film were beta-diketone chelates of Y, Ba and Cu. These chelates were evaporated at $137-264^{\circ}C$. The source vapors of Y, Ba and Cu were transported into hot zone by using Ar gas and $O_2$ gas was introduced separately.

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An Analysis of Tribological Properties of Metal Interlayered DLC Films Prepared by PECVD Method (PECVD로 증착된 금속층을 포함하는 DLC 박막의 기계적 특성 분석)

  • Jeon, Young-Sook;Choi, Won-Seok;Hong, Byung-You
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.19 no.7
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    • pp.631-635
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    • 2006
  • The properties of metal interlayered DLC films between the Si substrate and the DLC films were studied. DC magnetron sputtering method has been used to deposit intermediate layers of metals. And RF-PECVD method has been employed to synthesize DLC onto substrates of the silicon and metal layers. After we used metal Inter-layers, such as chromium, nickel, titanium and we studied tribological properties of the DLC films. The thickness of films were observed by field emission scanning electron microscope (FE-SEM). Also the surface morphology of the films were observed by an atomic force microscope (AFM). The crystallographic properties of the films were analyzed with X-ray diffraction (XRD), the friction coefficients were investigated by AFM in friction force microscope (FFM) mode. Tribological performances of the films were estimated by nano-indenter, stress tester measurement.

Synthesis of 3-mercapto-4H-pyrrolopyridine (3-멀?토-4H-피롤로피리딘의 합성)

  • 마은숙
    • YAKHAK HOEJI
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    • v.46 no.6
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    • pp.369-374
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    • 2002
  • Dilithiation of 4-(pivaloylamino)pyridine (5) followed by reaction with tetraisopropylthiuram disulfide(TITD) gave rise to 3-(diisopropyldithiocarbamato)-4-(pivaloylamino)pyridine (6). 3-Mercapto-4H-pyrrolopyridine(2) was synthesized from compound 6 by two methods. The first method was that compound 6 was treated with 5M-HCl to form 2-t-butylthiazolo[5,4-c]pyridine (7) and hydrolysed in refluxing 10% NaOH and solid NaOH to prepare bis(4-amino-3-pyridyl)disulfide (8). And compound 8 was reacted with 2,5-dimethoxytetrahydrofuran and NaBH$_4$ to afford compound 2. The second method was that compound 6 was hydrolysed with 10% NaOH and followed to react with 2,5-dimethoxytetrahydrofuran to form compound 11. And then compound 11 was treated with 20% ethanolic KOH solution to synthesize compound 2.

A study on the speech feature extraction based on the hearing model (청각 모델에 기초한 음성 특징 추출에 관한 연구)

  • 김바울;윤석현;홍광석;박병철
    • Journal of the Korean Institute of Telematics and Electronics B
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    • v.33B no.4
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    • pp.131-140
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    • 1996
  • In this paper, we propose the method that extracts the speech feature using the hearing model through signal precessing techniques. The proposed method includes following procedure ; normalization of the short-time speech block by its maximum value, multi-resolution analysis using the discrete wavelet transformation and re-synthesize using thediscrete inverse wavelet transformation, differentiation after analysis and synthesis, full wave rectification and integration. In order to verify the performance of the proposed speech feature in the speech recognition task, korean digita recognition experiments were carried out using both the dTW and the VQ-HMM. The results showed that, in case of using dTW, the recognition rates were 99.79% and 90.33% for speaker-dependent and speaker-independent task respectively and, in case of using VQ-HMM, the rate were 96.5% and 81.5% respectively. And it indicates that the proposed speech feature has the potentials to use as a simple and efficient feature for recognition task.

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The Synthesis of $ZrO_2+12 mol% CeO_2$ Powders by Coprecipitation Technique and Their Sintering Behaviors (공침법을 이용한 $ZrO_2+12 mol% CeO_2$ 분말합성 및 소결특성)

  • 강희복;김윤호
    • Journal of the Korean Ceramic Society
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    • v.31 no.8
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    • pp.879-885
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    • 1994
  • Coprecipitation technique was used to synthesize ZrO2+12 mol% CeO2 powders with ZrOCl2.8H2O and Ce(NO3)3.6H2O as starting materials. The powders were dried on different conditions such as distilled water, ethanol, and azeotropic distillation. The powders prepared by azeotropic distillation showed weak aggregation of particles and the average particle size of powders calcined at 85$0^{\circ}C$ for 1 hour was 0.19 ${\mu}{\textrm}{m}$. The optimum sintering temperature and holding time are 130$0^{\circ}C$ and 2.5~10 hours, respectively. Beyond the optimum conditions, a phase transition from tetragonal to monoclinic causes to produce cracks in the sintered bodies and to decrease the density.

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Mammalian Sialyltransferase Superfamily : Structure and Function

  • Lee, Young-Choon
    • Proceedings of the Korean Society of Life Science Conference
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    • 2002.12a
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    • pp.13-19
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    • 2002
  • To elucidate the regulatory mechanism for expression of sialyl-glycoconjugates and their biological functions, ninetheen sialyltransferase cDNAs including eleven by our group or co-works have been cloned and characterized so far. The cloned sialyltransferases are classified into four families according to the carbohydrate linkages they synthesize: ${\alpha}2,3-sialyltransferase$ (ST3Gal I-VI), ${\alpha}$ 2,6-sialyltransferase (ST6Gal I), GalNAc ${\alpha}$ 2,6-sialyltransferase (ST6GalNAc I-VI), and ${\alpha}2,8-sialyltransferase$ (ST8Sia I-VI). Each of the sialyltransferase genes is differentially expressed in a tissue-, cell type-, and stage-specific manner. These enzymes differ in their substrate specificity and various biochemical parameters. However, enzymatic analysis conducted in vitro with recombinant enzyme revealed that one linkage can be synthesized by multiple enzymes. We present here an overview of structure and function of sialyltransferases performed by our group and co-works. Genomic structures and transcriptional regulation of two kinds of human sialyltransferase gene are also presented.

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Chemical Preparation of $PbTiO_3$ Powder from Aqueous Solution (습식반응에 의한 $PbTiO_3$ 분말제조에 관한 연구)

  • 이경희;이병하;고영래
    • Journal of the Korean Ceramic Society
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    • v.22 no.2
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    • pp.39-43
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    • 1985
  • This study presents the results of an overall effort to detemine the applicability of the chemical wet process informing lead titanate electronic ceramics. Although pure lead titanate has not proven to be an important technological materials when prepared via conventional processing procedures this work is interesting as a study of chemical wet processing and a way of preparing pbTiO3 for study. The result obtained from this experiment were as follows ; Optimum synthesis condition which synthesize PbTiO3 by chemical wet process was obtained by firing at 50$0^{\circ}C$ after mixing $Pb(OH)_2$- gel and $Ti(OH)_4$ -gel at 7$0^{\circ}C$ for 4 hours.

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Pulsed laser ablation of hydroxyapatite in ethanol

  • Lee, Jung-Il;Ryu, Jeong Ho
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.24 no.5
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    • pp.219-223
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    • 2014
  • Pulsed laser ablation in liquid medium was successfully employed to synthesize hydroxyapatite colloidal nanoparticles. The crystalline phase, particle morphology, size distribution and microstructure of the hydroxyapatite nanoparticles were investigated in detail. The obtained hydroxyapatite nanoparticles had spherical shape with sizes ranging from 5 to 20 nm. The laser ablation and the nanoparticle forming process were discussed with explosive ejection mechanism by investigating change of surface morphology on target. The analytical results of XPS, FT-IR and Raman spectroscopy confirms that the stoichiometry and bonding properties of the hydroxyapatite nanoparticles are in good agreement with reported bulk hydroxyapatite materials.

An Approach on the Global Commerce Activation Regarding Culture Collision by the Use of M&A (M&A 협상성과에 기업간 문화차이가 미치는 영향에 관한 연구)

  • Park, Chong-Don
    • International Commerce and Information Review
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    • v.8 no.2
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    • pp.229-247
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    • 2006
  • The company culture is becoming usual term in business management field. That organization culture of these phenomenon becomes resource of company competitive power indeed, it is basing to logic for important leading person for elevation with systemicity. also, great many scholars do research to subject that is change management of company administration and there are not much example that companies succeed in change actually despite had announced treatise etc. This research tries to synthesize several research subjects by single model regarding confrontation(culture collision) phenomenon between culture that can happen in company through literature research and example analysis basically. Specially, try to classify and divide this by specific developing and arrange in each type with using much this culture analysis in negotiation analytics. Through this problem and suggestion point by this confrontation way in this culture negotiation side and culture risk management side of administration make try to.

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